Process of purifying insulating and lubricating oils



Dec. 1, 1936. P. B. RENFRl-:w 2,062,933

PROCESS OF PURIFYING INSULATING AND LUBRICATING OILS Original Filed Jan. 1l, 1930 5 Sheets-Sheet l Dim Ou.. E0 l Bac/f WAS/1 Tlv/vk 106 f C 'GNTRoblM-TCH me J9/Gl. '/41 FMEJ-wrrez ZWEI Dec. 1, 1936. P. B. RENFRW PROCSS OF PURIFYING INSULATING AND LUBRIGATING OILS E'Sheets-Sheet 2 Original Filed Jan. l1, 1950 67 7km/FORMER i l' m/ l ll I 36 67 i I 7S JT/L, TER/NG l! IEB f ZIE Baar WnsH PUMP mvo mi? Dec. 1, 1936.

.P. BA RENFREW PROCESS OF PURIFYING INSULATING AND LUBRICATING OILS Original Filed Jan. ll, 1930 5 Sheets-Sheet 3 Dec. l, 1936. p B RENFREW 2,062,933

PROCESS OF PURIF'YING INSULATING AND LUBRICATING OILS Original Filed Jan. ll, 1950 5 Sheets-Sheet 4 @f 57% we@ P. B. RENFREW PROCESS OF `PURIFYING INSULATING AND LUBRICATING OILS Original Filed Jan. l1, 1930 5 sheets-'sheet 5 DIR TY @nu Chf/w OIL. Pon M Patented Dec. 1, 1936 PATENT OFFICE PROCESS OF PUREFYING INSULATING AND LUBRICATING OILS Paul B. Renfrew, Fort Wayne, Ind., assigner to S. F. Bowser & Company, Inc., Fort Wayne, Ind., a corporation of Indiana Original application `lanuary 11, 1930, Serial No.

Divided and this application May 18,

1934, Serial No. 726,347

1 Claim.

My invention relates to a process or method for removing impurities from insulating and lubricating oils to restore the efficiency thereof, particularly removing solid impurities and water from oils used for electrical insulating purposes. My improved methods, however, may have a general application.

This application is a division of my co-pending application, Serial No. 420,062, filed January l1, 1930 and which has matured into Patent No. 1,962,463. In the present application I am claiming my improved purifying method. In my copending case I am claiming one novel apparatus by which the method may be carried out.

It is an object of my invention to provide a method for rendering anhydrous various types of oils including oils for heating and lubricating purposes wherein the oils are subjected to a particular treatment, including the utilization of positive pressure, the utilization of approximately specific temperatures, and the utilization of a vacuum closely approaching an absolute vacuum.

Another object of the invention is the provision of an improved system or method for conditioning a lter adapted to remove impurities from liquids.

A further object of the invention is an improved system and method for controlling a flow of liquid through a filter in a circulating system having as its source of supply used liquid to be purified.

Another object of the invention is the provision of an improved system and method for controlling the back wash of a filter and directing the back wash liquid out of the system.

An additional object of the invention is the provision of an improved system and method for draining a filter by directing the liquid out of the system.

Another object of the invention is the provision of a system and method for purifying oil em'- bodying provisions for replenishing the system with liquid from an outside source.

Other objects of the invention will appear hereinafter, the novel features and inventions being set forth in the appended claim.

Although my novel method of purication is not limited for use with the specific apparatus hereinafter to be described, and could be carried out in various ways, one preferred and novel apparatus and means for carrying out the method which I use for illustration is set forth in the accompanying drawings in which Fig. 1 is a diagrammatic View showing the relation of the various parts of a suitable apparatus setup for carrying out the method of my invention. This View represents the parts as the filter is being conditioned.

Fig. 2 is a diagrammatic view similar to Fig. 1, but showing the relation of the parts and the connections when the filter is operating.

Fig. 3 is a diagrammatic View similar to Fig. 1, but showing the relation of the parts and connections when the filter is being cleaned by back- Washing.

Fig. 4 is a diagrammatic view similar to Fig. 1, but showing the relation of the parts and ccnnections for effecting draining of the filter to a tank outside of the circulating system.

Fig. 5 is a sectional elevation of the filter shown in Figs. l to 4 inclusive.

Fig. 6 is a wiring diagram of the electrical circuits and connections of the apparatus shown in Figs. l to 4, inclusive, diagrammatically.

My method consists generally in the purication of oils such as insulating or lubricating oils by forcing them at high pressure through small orifices to remove solid impurities and suspended matter, heating the oil to a desired temperature and, through the utilization of a definite high vacuum, removing the water therefrom. The 2 method includes the filtering operation, the conditioning of the filter to perform such operation, the backwashing of the filter for cleaning and the draining of parts of the system as more particularly pointed out hereinafter. It also includes the y replenishing of the liquid supply in various Ways as will appear.

Reference is now made to the drawings in which, as stated, one suitable and preferred apparatus arrangement is shown for carrying out the method and processes of my invention. The various parts shown in Fig. 1, for example, except the transformer 2|, the barrel tank 22, the dirty oil backwash tank 23 and the conditioning oil tank 24, may be mounted upon a readily transportable platform or carrier truck so as to be portable to the place where the liquid, such as the insulating oil of transformers, or the insulating oil of electric switches, is to be treated to have the traces of moisture removed therefrom, as well as solid impurities. The valve structure shown at 25', in Figs. l to 4 inclusive, is illustrated therein diagrammatically for convenience. It is to be understood, however, that in practice the various valve parts |23 and |20, would be constructed as a unit for simultaneous movement by the control handle 19. Also, for sake of clearness, the heater element 26 for heating the filter 21 is shown separated therefrom in Figs. 1 to 4 inclusive; but, in practice, the heater element would be located in the base or under the filter 21, as shown in Fig. 5. The electric motor 28 and the vacuum pump 33 are also shown separated in the drawings for convenience but, in practice, the motor 28 for driving the clean oil pump 29 and the dirty oil pump 39, as shown in Fig. 1, for example, would be provided with a pulley on its shaft for driving a belt running on wheel 32, connected to the vacuum pump 33 for driving the latter. Mounted on the vacuum pump 33 is an oil seal tank 34 vented to the atmosphere at 35. The tank 34 is provided with a sight gauge 36.

An oil trap of suitable construction for preventing the removal of oil from the filter 21 into the vacuum pump is shown at 31 in Figs. l to 4 inclusive. Also shown in these figures is controller 39 for controlling by means of its operating lever 4l) the heater elements and motors which are supplied with electric current from the supply means 4|, as diagrammatically illustrated in Fig. 6.

A clean oil backwash tank is indicated at 42 and the bottom of this tank is connected by means of the pipe 43 directly to the backwash pump 45, which is connected to the electric motor 46 for operation thereby. A suitable pressure gauge 41 may be connected to the pipe 48 leading from the discharge side of the backwash pump 45.

After the oil is filtered it passes through the pipe 8| and then through the meter 56 into the pipe which directs the filtered oil into the tank 42. When the valve 52 of Fig. 1 is closed the oil will flow upwardly through the pipe 54 after the tank 42 becomes filled. The oil is thus directed into the top of the transformer 2 I. The member 59 may be of the displacement type such as that shown in the Hosmer L. Blum Patent No. 1,423,597, granted July 25, 1922, for an Improvement in meters.

The lter 21 is shown in sectional elevation, in Fig. 5 and is similar to that disclosed in my copending application Serial No. 302,743, filed August 29, 1928, for Apparatus for employing vacuum on porous laminated filtering mechanism. This filter comprises a cylinder 56 surmounted by a cap 51 supplied with mechanism on its lower central side for clamping together the multiple filter comprising a plurality of units each having a disc-shaped holder 58 with a disc filter element 59 mounted on the under side thereof to leave a chamber 69 for the flow of the filtered oil into the pipe 6| as indicated by the arrows. The oil to be filtered enters through the pipe 62 and can pass into the pipe 6I only through the plurality of filter elements 59, each of which is composed of very compactly Wound filter ribbon having thereon spaced-apart cross-bars to afford spacedapart grooves between the entrance sides and the discharge sides of the filter elements 59. These grooves form minute passageways of capillary proportions and microscopic dimensions because the ribbons are only four one-thousandths of an inch in thickness, the grooves being only four ten-thousandths of an inch in depth and each one-eighth of an inch in width with the raised cross-bars or cross-ribs a little wider. When such a ribbon three-eighths of an inch in width is wound very compactly into a disc it forms a filter element with minute pores distributed uniformly over the faces of the disc.

When the dirty oil pump 30 is operated by the -motor 28 and the valve 63 of Fig. 2 is open, used' oil from the transformer 2| will be pumped through the pipe 64, through the pump 30 into the pipe 65, and thence through a valve port 66 into the pipe 61 which is connected to the heater casting 26.

As shown at the bottom of Fig. 5, the heater casting 26 may be in the form of a closed casing for permitting the electric heater coils 68 to be embedded in the oil which flows into the casing or heater casting 26 from the pipe 61. `The oil flows out of the casing 26 through the pipe 62 and through the cover 51 into the chamber 69 in which the multiple filter is located.

It will thus be seen that the dirty oil pump 3|] pumps the used oil from the transformer 2| or the used oil from some other container and after passing it through the heater delivers it to the dirty oil pressure chamber 69. The dirty oil pump 30 and its piping connections should be such as to be capable of raising the hydraulic pressure up to approximately one-hundred pounds per square inch on the entrance sides of the filter elements 59. The porous filter elements 59 remove all carbon, dirt, sludge, and sedimentary deposits from the oil to insure thorough filtration of the solid particles of impurities in the oil.

In using the apparatus for treatment of insulating oil or used oil of a transformer it may not always be necessary to condition the filter 21, but when treating switch oils it is desirable to build cakes of sediment on the under entrance or pressure sides of the porous filter elements 59, to insure complete filtration of all suspended carbon particles and foreign matter present in such oils. Conditioning of the filter 21 is effected by pumping with the dirty oil pump 30 the used oil through the multiple filter for a suflicient length of time to build up the necessary cakes of filtered material on the bottoms of the filter elements 59. The extent to which the desirable cakes are being formed may be determined by the appearance of the filtered oil in the chamber into which the filtered oil is discharged from the pipe 6| as shown in Fig. 5. A sightglass window may be provided at 1| in the bottom of the casing 12 as shown in Fig. 1. When the oil becomes clear it is an indication that suflioient caking has been` effected on the bottoms of the filter elements 59.

The arrangement of the parts and the connections for effecting conditioning of the filter are shown in Fig. l. The clean oil pump 29 is used during the conditioning operation to pump the oil from the bottom of the casing 12 through the pipe 13. The pump discharges this oil through the pipe 14 and thence through the port 15 of the valve 25 into the pipe 16. This pipe is provided with a check-valve 11 which opens when the clean oil pump 29 builds up suflicient pressure. The oil then flows through the pipe 18 into the condition oil tank 24. The used oil during the conditioning operation is not sufliciently filtered and for that reason is discharged into a separate tank or container 24 and later re-filtered.

After the conditioning operation has been performed the control valve lever 19 may be immediately moved to the position shown in Fig. 2 for establishing connections for permitting the flow to continually circulate from the transformer through the filter and back to the transformer. During the operation of filtering, the motor 28 is driving both of the pumps 29 and 30. The valve 63 being open, the dirty oil pump 30 pumps the used oil from the transformer 2| through the pipe 64 and the filter screen |54 into and through the pump 30 to the pipe 65. The oil iiows through the port 66 of the valve 25 into the pipe 61 and thence through the.

heater casting 28, and from the latter into the pipe 62 which is connected to the filter chamber 69 as shown in Fig. 5. The clean oil pump 29 draws the purified oil from the bottom of the casing 12 into the pipe 13 and after passing through the pump 29 the oil is forced through the pipe 14 into the port 15 of the valve structure 25'. The oil then passes through the pipe 8| into the meter 59 and thence through the pipe 5I into the clean oil backwash tank 42. The Valve |40 of tank 42 being closed, the pump 29 will be able to force the oil from the tank 42 into the pipe 54 and thence back to the transformer 2l.

Both during the conditioning operation and during the filtering operation the valve structure 25 permits the application of a vacuum by means of the vacuum pump 33 to the vacuum chamber 18 shown in Fig. 5. The vaccum pump 33 is connected by means of the pipe 83 to the pipe 84 through the port 85 of the valve structure 25 and the pipe 84' is connected to the upper portion of the casing 12 as shown in Fig. 5. Figs. l and 2 illustrating respectively the con-4 ditioning operation and the filtering operation show that the port 85 connects the pipes 83 and 84 during both of these operations.

The vacuum effected by the vacuum pump 33 is applied directly to the chamber B8 on the upper or discharge sides of the filter elements 59. As the oil exudes through the multiplicity of pores it forms a thin film on the upper face of each filter element 59 so that the applied vacuum will immediately cause vaporization of the minute traces of water or moisture in the oil. When the flow of the oil through the lter elements is taking place comparatively rapidly on account of being connected to the oil casing of a transformer, the caking of solid impurities on the bottoms of the filter elements may not be sufficient to slow down the flow. Insulating oil for transformers has very little solid impuri ties, but it is very important to remove the minute traces of water or moisture from such insulating oil in order to restore the dielectric efliciency thereof. By slightly increasing the crosssectional area of the pores in the filter elements the rate of iiow of the oil may be increased and I therefore desire to add under such conditions the spreaders comprising the cones 86 in combination with the circular pans 81 having openings 88 at the centers of their bottoms as shown in Fig. 5. While the device shown in Fig. 5 of the drawings has been referred to in the present specification as a filter, it will be appreciated that by providing a device having a purality of relatively small openings or pores through which the oil may be forced under relatively high pressure, I have provided a most efficient device for render-F ing the oil anhydrous. This device for rendering the oil anhydrous is particularly effective due to the fact that the oil forced through the pores or openings under high pressures becomes very finely sub-divided, atomized or broken up, and in such state is subjected to a vacuum which preferably approaches very closely to a perfect vacuum, and furthermore, the removal of water or moisture from the gases is particularly enhanced by heating the oil toy temperatures below any temperatures which will tend to harm the oil. By thus heating the oil and subjecting it to a relatively high vacuum, I am enabled to use such relatively low temperatures as will cause the practically instant removal of water from the oil under the influence of the vacuum. It

will thus be seen that my invention is of twofold aspect: First, the treatment of the oil by forcing it under pressure through small pores or openings to filter the oil and/or by forcing the oil under high pressure through small openings while subjecting the discharge end of the opening to a relatively high vacuum, and while heating the oil to temperatures below oil carbonization temperatures whereby toI render the oil anhydrous. The cones 8G and the pans 81 alternately arranged as shown in Fig. 5 are supported by means of the rods 89 and the spacers 98 which are suspended from the under side of the top of the casing 12. The filtered oil descends from the pipe 6l as indicated by the arrows and flows radially outwardly on the upper surfaces of the cones 86 and radially inwardly on the pans 81, thus spreading the oil over a large area in a small space and affording ample opportunity for the last traces of moisture that may be in the oil after leaving the chamber 60 to escape by additional vaporization, through the pipe 84', into the oil trap or seal 31 shown in Fig. 2 and thence to the pipe 84, valve 25, pipe vacuum pump 33 and the oil drip tank 34 to the atmosphere through the vent 35.

The oil seal 31 is connected in the vacuum pipe. It may be connected as shown in Fig. 2 between the pipes 84 and 84. The construction of one suitable form of oil seal is disclosed in my aforementioned co-pending application, Serial No. 420,062. However, any suitable liquid separating trap, various types of which are well known in the art, may be used.

When the vacuum pump is operating and a vacuum is being applied to the chamber 10 through the pipe 84', any oil which passes through the pipe 84 either as a liquid or in the form of a mist will be stopped by the oil trap. It will thus be seen that the oil trap is provided in connection with the vacuum chamber of the filtering apparatus and that this oil trap is connected directly in the vacuum line. The purpose of this oil trap is to prevent possibility of any oil, either liquid or in the form of a mist, passing to the vacuum pump. If this should occur the vacuum pump may become flooded and the efficiency of it Alowered. considerably.

The function of the vacuum pump is the removal of moisture from the insulating oil. vacuum pump lowers the atmospheric pressure on the filtered oil to a point where the moisture in the oil boils violently. This causes the moisture to expand approximately sixteen hundred volumes into its vapor phase, thereby enabling it to be separated entirely from the oil. This permits the entrapped moisture to be readily removed from the oil by vacuum treatment leaving it in a completely anhydrous condition.. 'I'he application of the vacuum makes it unnecessary to heat the oil up to a temperature of 212 degrees Fahrenheit which is necessary to boil water at atmospheric pressure. As hereinafter explained, the electric heaters keep the temperature at from,

to 160 Fahrenheit which is suicient to assure maximum speed in dehydrating and enabling the vacuum to operate at its highest degree of efciency.

The vacuum pump after removing the liberated water from the vacuum chamber expels it to the atmosphere by condensing it back to water in the oil seal tank 34. The condensed water may be periodically removed from the oil seal tank 34 by the open Siphon method.

A closed manometer |83 is placed in the vacu- 75 um line by being connected to the pipe 83, Fig. 2. This manometer is located between the control valve 25' and the vacuum pump to indicate the degree of vacuum under which the equipment is operating. rIhe degree of vacuum found desirable is within ten to twenty millimeters of a perfect Vacuum.

The tank 34 which is mounted on the vacuum pump is partly filled with oil and serves as a constant vacuum seal. The level of oil in the oil seal tank for eicient operation of the vacuum pump may be indicated in connection with the glass gauge 36. That is to say, the eiiicient operation of the vacuum pump may be predetermined and the depth indicated on the tank for efficient operation and by means of the glass gauge the oil in the tank 311 may be brought to the proper depth for such efficient operation.

An air release valve |64 may be connected to the top of the lter 21 so as to communicate with the chamber 69. This air release valve |94 may be similar to the ordinary air release on a steam radiator and when this valve is open the used oil to be filtered may flow into the chamber 69 until all of the entrapped air has passed through the air release valve |64 which may be indicated by the flow of oil from the air release |94, upon which this release is closed and kept closed during the operation of the apparatus.

A two-hundred and fifty pound pressure gauge |95 is connected to the dirty oil discharge line. This pressure gauge may be connected to the pipe 61 between the control valve 25 and the filter 21 as shown in Fig. 2 to indicate the pressure under which the system is operating during the purifying process. Another pressure gauge 41 which may also be a two-hundred and fifty pound pressure gauge is located in the discharge line of the backwash pump 45, to indicate the backwash pressure as shown in Fig. 3.

Since transformers are often located in outside positions exposed to atmospheric conditions the temperature of the oil therein will vary at different seasons of the year and therefore it is desirable to provide a plurality of heating elements 68, any one or more of which may be connected in circuit so as to vary the temperature of the iniiowing used oil. In Fig. 6 is shown a Wiring diagram of the circuits and connections for the electric heater elements 68 and also for the electric motors 28 and 46. The controller 39 of Fig. 1 is diagrammatically illustrated at 39 in Fig. 6 by means of a switch lever 40 operating on switch contacts which are all in the same plane, although it should be understood that the controller 39 shown in Fig. 1 may be of the type having a vertical shaft and the contacts at different elevations.

When the main line switch |66 of Fig. 6 is closed the supply mains 4| will be connected to the conductors |61 and |68. When the switch lever 40 is in a vertical position or off position the circuit will remain open, but when the switch lever 46 is moved in an anti-clockwise direction into engagement with the stop or abutment I I0, it will be electrically connected with the switch contact I I I and 'thereby close the electric circuit through the conductor |91, backwash motor 46, conductor I I2, switch contact I I I, switch lever 46 and conductor |66. This circuit is established between the supply mains 4I.

When the switch lever is moved to its full line position shown in Fig. 6 it will engage the semi-circular contact M and close the circuit through the conductor |01, motor 28, conductor I I3, contact M, switch lever 40 and conductor' |98. It will thus be seen that when the dirty oil and clean oil motor 28 is operating no circuit can be established to the backwash motor, and when the backwash motor is operated the current is out off from the dirty oil and clean oil motor 28. Furthermore, when the switch lever 40 is in its full line position shown in Fig. 6 none of the heater elements 68 are as yet connected in circuit and therefore the dirty oil and clean oil motor 28 may operate the dirty oil pump and clean oil pump independently of the operation of the heater elements. Therefore during hot weather or when the transformer oil has already been sufficiently heated during operation the heater elements may be kept out of circuit.

When desired, particularly in connection with the treatment of insulating oil for switches, the switch lever 40' may be moved into cont-act with the arcuate contacts M1, M2, M3, M4 and M5 successively until the switch lever 40 abut-s against the stop |I.4. The stop II4 compels the switch lever 40 to be moved in an anti-clockwise direction when it is desired to` operate the backwash motor 46. When the switch lever 40 is on any one or more of the contacts Ml to M5 it always remains in engagement with the semicircular contact M. Consequently whenever any of the heating elements are operated the dirty oil and clean oil motor 28 is also operated. When more than one heating element 68 is connected in circuit the current flows through the same in multiple from the conductor ||5 to the conductors I I6. It should be understood that the heater casting 26 is entirely closed so that when the oil enters from the pipe 61 it completely submerges the heating elements 68. The oil to be filtered is circulated through the heater casting 26 completely submerging all of the heaters 68 and the oil is therefore subjected to the maximum amount of heat created by each of the heater elements 68.

As shown in Figs. 1 and 5, the oil may be heated by the heating elements 68 in the chamber |69 before it iiows through the pipe 62 to the chamber 69 of the lten 21. It is preferable by means of the electric heaters to keep the temperature of the oil at to 160 Fahrenheit so as to assure maximum speed in passing through the porous filter elements 59 and in being dehydrated in the chambers 60 and 10. In other Words, by heating the oil its viscosity is reduced and its oW increased through the filter elements and, moreover, the higher temperature enables the vacuum to operate at its highest degree of efficiency without necessitating such a high temperature as 212 Fahrenheit which would be necessary at atmospheric pressure to; effect vaporization of water.

One electrical switch 39 as shown in Fig. 6, which switch may be in the form of the controller 39 shown in Fig. 1, controls the starting and stopping of all electrical equipment in the entire system. The controller lever 46 is mounted in convenient position for operation and by means of this single lever the dirty oil pump 36 and clean oil pump 29 may be operated by the motor 28 and the backwash pump 45 may be operated by the motor 46 and one or more of the heater elements 68 may be co-nnected in circuit only when motor 28 is in operation. The dirty oil pump 30 and the clean oil pump 29 may be operated with or without the heaters. At no time can the backwash motor 46 be started without rst returning the control handle 40 to the ofi position. Seven positions may be designated on the controller top marked respectively BL W., off, 2, 3, 4 and 5, as illustrated in Fig. 1. As the temperature rises one or more of the heating units can be disconnected to obtain the desired temperature and thereby use a minimum number of heating units.

A thermometer may be mounted in the flow line of the pipe 62 and b-y means of this thermometer the temperature of the oil may be observed so that it may be regulated by meansv ofthe electric heater and the switch mechanism for controlling the same. By having the single controller connected as shown in Fig. 6, a onepoint electrical control for the entire system illustrated in Fig. l is afforded.

The multiple valve shown diagrammatically at in Figs. i, 2, 3 and 4 has a single operating lever 'I9 and thus affords a one-point control for the conditioning, filtering, backwashing and draining operations. The control valve 25' of the system consolidates and combines the manipulation of many valves into a single unit having only tourl operating positions which may be designated filter, backwash, drain and condition. This multiple valve is simple in construction but positive in operation. It is so designed that regardless of the direction of the flow of the oil, whether' clean oilor dirty oil, each kind of oil is confined to a separate compartment in the valve body so that the clean oil is never contaminated by the dirty oil. The vacuum compartment in the valve body is placed between` the clean oil compartment and the dirty oil compartment to assist in preventing contamination, and the valve compartments are so arranged that the vacuum compartment will be sealed from the atmosphere.

The specic construction of the multiplevalve 25. is set forth in detail in my aforementioned co-pending application Serial No. 420,062. However., inasmuch as the specific details of construction are not material to my new process or method it is not believed necessary toI set forth thedetails of construction of the valve herein. Suiiice'to say that the valve is provided with annular recesses as indicated diagrammatically in. Figs. 1, 2, 3 and 4, which form the several fluid passageways in the valve body. The several recesses are separated one from the other, ashas been stated, but all are cut from a single valve body |20, movement of which is controlled by operating lever 'I9 so that all the valve passageways are simultaneously controlled by the single' operating lever. The recess 66, the recess 85;..andthe two recesses l5 and |34, may be separated by being displaced vertically along the valve body |20, the two recesses 15 and |34, however, being in the same plane. Recess 6B is the dirty oil compartment, recess 85 is the vacuum compartment, and recesses 'l5 and |34 constitute the clean oil compartments. As previously indicated, the vacuum compartment lies vertically between the dirty oil and clean oil compartments and thus aids in separating them so as to prevent oil contamination. Dirty oil compartmentcooperates with pipes 65, 67, |32 and |33; vacuum compartment S5 cooperates with pipes 84 and B3; clean oil compartments |34 and T5 cooperate with pipes 76, |36, 3|, |31 and |43, in the various positions of the valve body, all as indicated in Figs. 1, 2, 3 and 4.

Pipe |32 is connected to the dirty oil backwash tank 23, and pipe |33l is connected to the lower part ofthe case 56 of the filter, as shown in .Figg 5. A checkvalve |35 is located in the pipe |33 to permit the flow of backwash oil from the chamber 69 of the filter toward the tank 23. Pipes 83 and 84 are in the vacuum line, as illustrated in Fig. 1.

W'hen the valve 25 is in filtering position illustrated in Fig. 2, the port'i5 at the lower end of the valve |2`|l` connects the pipes i363 and 8|. The pipe |361 is connected to the pipe 14. When the Valve 25 isin the position illustrated in Fig. 2 and the motor operates the clean oil pump 29, oil may be dra-Wn from the chamber 'it' to the pipe '13..- and the pump 28 discharges the oil into the pipe |41 and thence into the pipe |35. A loaded valve |33` is connected in a by-pass betweenY the suction and discharge ports of the clean oil pump' 29 so that when the back pressure or head. inthe pipe |33 exceeds a predetermined' limit the oil will be directed through the valve |39` back to the pump 29. The oil pumped into the pipe |36 passes through the port 'l5 into the pipe gland thence through the meter 5G intoV the pipe 5| and the closed tank 425. The` valve |43 being closed the oil Will pass through the cleanoil backwashtank 42 into the pipe 54 and thence to the transformerl 2|.

At the same time that clean oil is being taken from the chamber 'F3 and pumped to the transformer 2|, used oil is being taken from the transformer and pumped by means of the dirty oil pump 33 into the pipe 35. A loaded valve |41 in the by-pass pipe |42 permits return of the oil to the suction side of the pump 33 if the head in the pipe. |55 exceeds a predetermined limit. The pipe 65 directs the oil through the port 56 of the control valve 25 into the pipe 6l and thence through the heater casting 255 into the pipe 62 and4 thence into the filter chamber 69 as shown infFig; 5;

Also, at the same time that oil isA being circulated in the system illustrated in Fig. 2 by being drawn from the transformer simultaneously with the supply of oil to the transformer, the vacuum pump 33 is being operated, the port 85 of the valve |20-establishing communication between the closed chamber 'lll and the vacuum pump 33 through the oil trap 3l and into the oil seal tankk 34. Since the pulley 32 on the shaft of the vacuum pump 33 is connected by a belt to the shaft of the motor 28 the vacuum pump will be operated at the same time that the clean oil pump 29 and the dirty oil pump 3D are being driven.

Since the clean oil pump 29 and the dirty oil pump are provided with by-passes with loaded valve |39 and |4| therein respectively each set at about one-hundred pounds, the pumps cannot be stalled and consequently the motor 28 will continue to drive the vacuum pump 33 at all times during the operations of conditioning and filtering illustrated respectively in Figs. 1 and 2. A singlev motor 28 may therefore be used to drive the vacuum pump 33, as well as the clean oil pump 29. and the dirty oil pump 35.

The operation of the system illustrated in Fig. 1 for the purpose of conditioning the lter shown in Fig. 5 will be best understood by following the steps in the positioning of the switch lever 40 of Fig. 6 and the position of the valve operating lever 'I9 of the valve structure diagrammatically illustrated at 25 in Fig. 1. With the switch lever 40' in position M-l, 2, 3, 4, 5, depending upon the amount of electric heat required, the operating valve lever 1S is moved to the condition position. This position is diagrammatically illustrated in Fig. 1. With the main line switch |06 closed and the switch lever` 40 in position to start the motor 28 and throw into circuit one or more of the heating elements 68, the clean oil pump 29 and the dirty oil pump 30 and also the vacuum pump 33 will be operated. The port 15 at the lower end of the valve |20 will establish communication between the pipe |36 and the pipes 16 and 18 through the check-valve 11 to the condition oil tank 24. The check-valve 11 opens from the pipe 16 to the pipe 18 but will prevent return flow. Used oil is pumped by the dirty oil pump 30 through the port 66 and the heater 26 to the filter 21 while the ltered oil is pumped by the clean oil pump 29 through the port 15 to the tank 24. At the same time the port is in the vacuum line and Vacuum is being applied to the filtered oil. However, in order to bring the lter into proper condition for eflicient filtration, the oil is pumped through the iilter into the tank 24 until suicient caking of the solid particles occurs on the bottoms of the ilter elements 59 to result in Very eflicient filtration. By observing the oil at the bottom of the casing 12 through the sight-glass window 1| the progress of the caking may be determined by the condition of the oil. When it becomes clear it is an indication that sufiicient caking has taken place.

The used oil that is used for the conditioning" operation is stored in the condition oil tank 24 and later reltered. After the conditioning operation has been eiected the control valve lever 19 may be moved through to its lter position illustrated in Fig. 2. In the filter position of the valve structure the communication to the pipes |32 and |33 is cut oif and also the communication to the pipes 16 and |31. In other words, the pipes |32, |33, 16 and |31 are closed at the valve casing by the valve |20.

After the conditioning operation has been performed by the formation of cakes of impurities on the bottoms of the lter elements 59, the pressure exerted by the dirty oil pump on the liquid in the chamber 39 is about one-hundred pounds per square inch.

The rapidity with which the thickness ofthe cake on the bottom of each filter element 59 increases depends upon the amount of foreign matter in the oil. In the treatment of insulating oil of transformers the increase of the cakes is very slow because of the very small quantity of solid particles of impurities in the transformer oil, but when the filtering system is used for treatment of switch oils the cakes increase in thickness more rapidly and ultimately the capacity of the multiple filter shown in Fig. 5 is materially reduced and the cakes must be removed by backwashing. A two-hundred and fifty pound pressure gauge is located in the dirty oil discharge line as indicated at |05 in Fig. 2 and by observation of this pressure gauge it may readily be determined when backwashing is necessary or advisable in such a circulating system as that illustrated in Fig. 2 wherein used oil is being continually taken from the transformer 2|, purified and sent back to the transformer. When it is desired to increase the pressure on the oil in the chamber 69 the loaded valve |4| may be adjusted for such increased pressure. For instance, if the caking increases the pressure may be increased by increasing the load on the valve |4| and the resulting pressure will be indicated on the pressure gauge |05. When the pressure has been increased to two-hundred pounds per square inch the eiiiciency has been materially decreased and 'backwashing is then advisable.

To effect backwashing the switch lever 40 of Fig. 6 is brought back to off position. The operating lever 19 is then moved 90 from lter position to backwash position. The positions of the valve ports when the lever 19 is moved to backwashing position are illustrated in Fig. 3. As shown in Figs. 3 and 5, when the valve structure 25 is in backwashing position the port 15 at the lower end of the valve |20 establishes communication between the pipes |31 and |43, the latter being connected` to the lower portion of the clean oil chamber 10. The pipe |31 is connected to the pipe 48 which leads to the discharge side of the backwash pump 45. The suction side of the pump 45 is connected by means of the pipe 43 to the bottom of the clean oil backwash tank 42.

The two-hundred and fifty pound pressure gauge 41 is connected to the pipe |31 as shown in Fig. 3 and a loaded valve |44 is located in a bypass |45 around the backwash pump 45. When the backwash pump pressure exceeds a predetermined limit the Valve |44 permits the oil to flow back to the suction side of the pump through the` by-pass |45, thereby preventing the pump from stalling. The backwash pressure may be varied by adjusting the loaded valve |44.

In order to effect operation of the backwash pump 45 the switch lever 40 is moved from its OIT position into engagement with the contact ii i against the stop I I0 shown in Fig. 6. A circuit will then be established between the conductors |01 and |08 through the backwash motor 46. Clean oil will then be pumped from the clean oil backwash tank 42 through the pipe 43 when the valves |40 and |49 are open and valves |48 and |46 are closed. The clean oil will be discharged into the pipes 48 and |31 when the valve |46 is closed. The oil then passes through the port 15 of the valve 20 into the pipe |43 and thence into the chamber 10 and up through the pipe 6| shown in Fig. 5 into the chambers 60 and downwardly through the pores of the filter elements 59 to force the cakes of impurities therefrom by hydraulic pressure. This back- Washing operation is preferably performed at a pressure of two-hundred pounds per square inch on the upper surfaces of the filter elements 59.,

This backwashing operation dislodges the cakes of sediment quickly and removes a portion of it from the chamber 69 of the filter 21 by the iiow of the mixture of oil and impurities through the pipe 33. The flow of oil at this time through the pipe 62 is blocked or shut oi by the closure of the pipes 65 and 61 at the upper end of the valve I 20 as shown in Fig. 3.

The port 66 at the upper end of the valve |20, however, establishes communication between the pipes |33 and |32 so that the mixture of impurities from the cakes and the oil may be directed into the dirty oil backwash tank 23. The remaining large particles of impurities which are removed by the backwashing pressure from the bottoms of the lter elements 59 are received on the tops of the cup-shaped holders 58 and the disc |41. The impurities on the tops of the holders 58 and the disc |41 are removed to the bottom of the chamber 69 by the washing operation and may then be removed from the casing 56 periodically through a handhole the bottom of the casing 56.

inasmuch as the backwashing pressure is to be exerted so that the ow of oil mixed with im- `75 i.

Provided at purities shall be only through the pipe |33 to the dirty oil backwash tank 23, the vacuum pipe line is also closed at the valve |20 between the pipes 83 and 84. By referring to Fig. 3 it will be seen that the pipes 83 and 84 are closed at the valve |20 since the port 85 is located distant from the pipes 83 and 84 when the lever 10 is in backwashing position. Therefore, exit from the chamber 10 is cut off except through the pipe 6| and the chambers 60 at the tops of the filter elements 53 and exit from the chamber 69 is cut off except through the pipe |33 which leads through the port 66 to the pipe |32 and thence to the dirty oil backwash tank 23. It will also be seen that when the switch lever 40 is in backwashing position the motor 28 is cut off from the source of electric supply and therefore the clean oil pump 20 and the dirty oil pump 30 are not operating during the backwasln'ng period.

The backwashing pump is capable of creating a pressure of two-hundred pounds per square inch which is sufficient to fully restore the original capacity of the system, and this backwashing pressure is always available. When this backwashing operation is applied to the ltering apparatus it quickly and completely removes the cakes of impurities which have been formed during the ltration process.

Besides observing the pressure being exerted on the filtering apparatus as indicated by the pressure gauge |05, the rapidity with which the oil is being filtered may also be checked by observing the number of gallons of oil passing through the meter 50. In other words, by means of the meter 50 the rate of flow through the system may be observed at any time and thereby determination may be made as to when it is necessary to backwash to regain the rated capacity of the system.

After the backwash operation has taken place the filter chamber 10, the pipe 5| and the chambers are left full of clean oil which should not be wasted. Therefore in the next operation the valve control lever 19 is moved to drain position. The connections of the system for draining are illustrated diagrammatically in Fig. 4. The switch lever 40' having rst been moved to ofi position when the backwash pump is stopped, is now moved to the position shown in full lines in Fig. 6 after the lever 19 has been moved to drain position illustrated in Fig. 4. The switch lever 40 may be at M or M-|, 2, 3, 4 or 5. The driving of the motor 28 will operate the clean oil pump 29 and the dirty oil pump 30, but the pipe 65 being closed by the valve |20 the dirty oil pump 30 will merely operate through the by-pass valve |4|. The clean oil pump 29, however, will pump the oil in the chamber 10 through the pipe 13 and discharge it through the pipes 14 and |36 and thence through the port |34 into the pipe 8| and through the meter 50 into the pipe and then into the clean oil backwash tank 42. The va-cuum line at this time will be closed by the valve |20 closing the pipes 83 and S4. After the oil has been sufficiently drained from the chamber to bring the level of the oil below the lowermost pan 81 the system may be operated to effect iiltration for insulation oil or the filtering mechanism may be reconditioned for the purification of switch oils.

The filter screen |54 may be an enclosed casing with a cup-shaped screen therein to prevent coarse particles of material from entering the pump 30. The valve |53 is normally closed, but when opened, a sample of oil may be taken from the transformer to test its dielectric strength. The valve |52 may be used to drain the dirty oil from lter 21 when the latter is inoperative and backwashing becomes necessary.

Means are also provided for transferring oil from one receptacle to another such as barrel to barrel, or barrel to underground tank. The control valve 25 may be set in any position desire-d while the apparatus is operated for transferring oil or other liquid from one receptacle to another. The controller 39 is, however, set in backwashing position. That is to say, the switch lever 40' of Fig. 6 is moved against the stop H0 so as to engage the contact and thereby close the circuit through the backwash motor 46 between the conductors |01 and |08.

If now the valves |40 and |49 are closed with the valves |48 and |46 open, oil may be pumped from the barrel or tank 22 and transferred through the pipes 48 and |5| into the pipe 54 and thence into the transformer 2|. Due to the fact that there are no valves in the pipe line 54 between the transformer 2| and the clean oil backwash tank 42, oil may be pumped from the barrel or tank 22 into said clean oil backwash tank 42. It should be understood that the oil in the tank 22 should be purified oil in condition for use in the transformer 2 i, but if there should be any moisture therein it will be removed in the circulating system of purification. The oil that is introduced into the top of the transformer casing 2| is taken out from the bottom thereof through the pipe 54 when the valve 53 is open and the dirty oil pump 35 is operated with the control valve in the position indicated at 25 in Fig. l.

When desired, the tank 42 may be drained into barrels '22 by opening the valves |40 and |48 when the barrel is connected, as shown in Fig. 3. A connection to an outside barrel or tank may also be made at 52 in which event the operating lever 19 of the control valve may be set in drain position as shown in Fig. 4 and the switch lever 40 moved onto contact M so as to operate the motor 2B. In this manner clean purified oil may be withdrawn from the chamber 10 shown in Fig. 5 through the clean oil pipe 13 and delivered to the container connected to valve 52.

In order to transfer oil or other liquid from one tank to another both located outside of the unit; this may be done by operating the backwash pump 45 while the control valve is in any of the four operating positions with the valves |48 and |46 open and the valves |40 and |49 closed. One barrel may be connected to the pipe 43 through the valve |48 and the other barrel 42 connected to the pipe |31 through the valve |46. This may be seen by referring to Fig. 3. When the backwash pump 45 is operated the liquid may be withdrawn from the tank 22 and pumped through the pipes 43 and 48 and thro-ugh the valve |46 to the other barrel. By closing the valve |48 and disconnecting the barrel 22, the valve |40 may be opened and by operating the backwash pump 45 clean oil may be withdrawn from the tank 42 and directed through the valve |46 to a separate barrel or container. When oil is being transferred from the barrel 22 or from the tank 42 to a separate container connected to the valve in the pipe |31 the valve |49 should be kept closed.

At noV time should oil in condition oil tank 24 and dirty oil tank 23 be pumped direct into top of transformer 2|, as this oil may not be 75 either filtered or dehydrated. Pipe 64 can be connected to condition oil tank 24 and this oil filtered in the regul-ar Way as this oil is dehydrated in the conditioning process but not completely filtered of suspended carbon particles. In the same manner oil in the dirty backwash tank 23 may be allowed to stand to remove the coarser particles of impurities by sedimentation and then the oil in the upper part of the tank 23 may be filtered in the regular Way.

If transformer casing is to be filled with oil before the same is started into operation, this may be done by using the backwash pump to. pump oil from barrel 22 through the pipes 43, 48, |5| and 54 while the valves |48 and |46 are open and the valves |40 and |49 `are closed. After a transformer is operated for some time the filtering unit may be connected thereto to effect the filtering operation illustrated in Fig. 2. Prior to such treatment the filter may be conditioned.

Fig. 1 shows the equipment and connections for conditioning of the filter. Upon operating the controller 39 to start the motor 28 the dirty oil pump 30 will be driven and so also the clean oil pump 29 to effect circulation of the oil While the parts are connected as illustrated in Fig. 1. The oil used during the conditioning of the filter 2`| is pumped intok the condition oil tank 24. After the filter 21 is conditioned this oil may be introduced into the transformer 2| by setting the valve apparatus illustrated at 25 in Fig. 2 in filtering position and also in such position as to connect the dirty oil suction lineV 64 to the condition oil tank 24. After the oil in the condition oil tank 24 has been filtered and delivered to the transformer 2|, the latter is connected to the pipe 64 by opening the Valve 63, whereupon the oil in the transformer 2| will be continued to be filtered as illustrated in Fig. 2.

If there is not sufficient oil in the system at such time to completely fill the tank 42 and maintain proper depth of the oil in the transformer casing 2|, more oil may be introduced into the system by means of the backwash pump pumping oil from a separate tank 22 into the transformer casing 2| until after continued filtering operations the tank 42 is completely filled and the proper depth of oil maintained in the casing 2|. It should be particularly noted that the purified oil is introduced into the transformer casing 2| as fast as the used oil is being withdrawn therefrom so that the system is entirely automatic While the proper depth of oil is maintained in the transformer to completely submerge the parts which it is intended to insulate. Y

Obviously those skilled in the art may make Various changes in the various process steps and methods hereinbefore described, or could make various changes in the details and arrangements of the apparatus disclosed, or could substitute other apparatus than that specifically described for carrying out the several methods Without departing from the spirit and scope of the invention as defined by the claim hereto appended. I wish therefore not to be restricted to the precise illustrative embodiment herein disclosed but only as indicated in the following claim.

I claim:

The herein described process which consists in forcing oil under pressure of approximately pounds per square inch through a plurality of relatively minute orifices, distributing the liquid over relatively large areas while subjecting the same to a relatively high vacuum and thereafter drawing the filtered oil from said surfaces and returning it to its source of use in a continuous cycle.

PAUL B. RENFREW. 

